Chemicals That Terminate Pond Algae

Water "features" such as swimming pools and fish ponds harbor harmful organisms and chemicals, such as pond algae and pond weed, organic matter and sludge, ammonia, chlorine and phosphates. Algae are small organisms that can turn the water cloudy and can produce scum on the surface, preventing sunlight from penetrating the water. They also release harmful toxins to water. Different chemicals are available to keep pond algae under control.

Algicide

• Regular use of algicide can rid a pond of algae and cyanobacteria (blue/green slime) as well as reduce deposits of plant material that can clog filters and pumps. Three types of algicides are available,

  Copper salts are used in ponds to prevent and kill algae formation. However, regular copper usage can stain the walls of the pond.

  Quats (quaternary ammonium salts) act as surfactants, lowering the surface tension of water and resulting in algae cell wall rupture and cell death. Quats cause foaming on pond surface and are generally a preventive measure for algal growth. Polyquats are non-foaming algicides used to combat green algae, chlorine-resistant mustard algae and black algae.

  Most algicides require specific concentrations that may cause, if used improperly, harm to fish, swimmers and aquatic livestock. They are not well-suited for ponds with high flow-through rates, which can rapidly dilute or flush away the algicide, or for pond owners on a budget: Algicides are more expensive than environment-friendly pond chemical alternatives.

Water Clarifier

• Water clarifiers, sometimes referred to as water polishers, work on particulates such as silt, organic matter, algae, oils, lotions and metals. They are a polymer (large molecule composed of repeating structural units connected by covalent bonds) with a positive ionic charge. Suspended particulates are mostly negatively charged. Therefore, they get attracted to the positive ends of the polymers (coagulation). This leads to formation of large, filterable particles. Accumulation of these large filterable particles results in the formation of much larger aggregated clusters (flocculation). A water clarifier must be able to remove both oil and the organic matter from the water, by working through a complete process of coagulation and flocculation. This combined action helps in the filtering of these particles, leaving the pool or pond water clean and clear.

Ammonia Binders

• Ammonia binders or ammonia removers act by binding ammonia that may be present in non-toxic form, until it can be processed by the biological filter of the pond. Sudden increase in the levels of ammonia may be due to death of fish, improper aeration or accidental death of the bacterial bed (from excessive use of antibiotics or cleaning agents) in the pond. Use of ammonia binders should be kept to a minimum and only for emergencies. If the pool or pond is stressed, one should first transfer the fish to a tank and then increase the oxygen level by rebuilding the bacterial bed.